Hoist Mechanism

Abstract

The hoist mechanism includes four winches which are mounted on the base of a frame structure having upstanding supports on the base. The winches are connected to a common drive shaft rotatably mounted on the base. A pair of upper and lower guide rollers are associated with each of the winches and are mounted on the upstanding supports. Each winch has a length of cable, a portion of which is wound on the winch and a portion of which is trained over the guide rollers and then secured to one corner of a panel which is horizontally disposed over the base. Each cable is trained over a movable sheave assembly which is resiliently biased to place tension on the cable. A slip clutch is located in the drive connection between the drive shaft and each winch to stop rotation of each winch when a predetermined tension is placed on each cable wound on each winch, such as when a corner reaches its upward limit of travel.

Description

The present invention relates to a hoist mechanism for raising and lowering a horizontally disposed panel, such as a roof panel of a collapsible container, on a frame structure which includes a base and upstanding supports. As such, the present invention provides a simple and compact hoist mechanism including a plurality of cables which are fixed to the horizontally disposed panel at spaced apart locations thereon, Each of the cables is trained over upper and lower guide rollers on the upstanding supports and then wound on a winch. The winches are driven by a common drive shaft. To minimize misalignment of the panel when it is raised and lowered and to limit the tension placed on the cables, each of the winches has a slip clutch associated therewith. When the tension on one of the cables reaches a certain point, the clutch associated with the winch on which the one cable is wound will slip and further rotation of the winch is prevented. To minimize sway when raising and lowering the panel and to minimize slack in the cables when the panel is in a fully raised position or a fully lowered position, a spring tensioning device is associated with each winch on each cable for maintaining tension on each of the cables in all positions of the panel.

A general object of the present invention is the provision of a simple and inexpensive hoist mechanism for raising and lowering a horizontally disposed panel.

Another object of the present invention is the provision of a hoist mechanism for raising and lowering a horizontally disposed panel in which little, if any, sway or misalignment of the panel is encountered during the raising and lowering thereof.

Another object of the present invention is the provision of a hoist mechanism for raising a roof panel of a collapsible container.

Another object of the present invention is the provision of a hoist mechanism for raising and lowering a horizontally disposed panel in which proper vertical translation of the panel between a fully lowered position and a fully raised position over a period of continued use of the hoist mechanism is ensured.

Another object of the present invention is the provision of a hoist mechanism for raising and lowering a horizontally disposed panel by means of a plurality of cables connected to the panel wherein the length of each cable is maintained uniform during raising and lowering of the panel.

Another object of the present invention is the provision of a hoist mechanism for raising and lowering a horizontally disposed panel wherein each corner of the panel is raised to its upward limit of travel so that each corner, after the panel is raised, will be in proper position to be locked in place without placing excessive tension on any one of the cables.

Another object of the present invention is the provision of a hoist mechanism for raising and lowering a horizontally disposed panel by means of a plurality of cables connected to the panel wherein tension is maintained on all of the cables in all positions of the panel to prevent slack from developing in any one of the cables.

Another object of the present invention is the provision of a hoist mechanism for raising and lowering a horizontally disposed panel by means of a plurality of cables connected to the panel wherein each cable is connected to a winch and the maximum tension is limited to a predetermined value to prevent damage to the cables.

Still another object of the present invention is the provision of a mechanism for raising and lowering a horizontally disposed panel by means of a plurality of cables each connected to the panel wherein each cable is connected to a winch and the winches are driven in synchronous relationship by a common drive shaft.

These and other objects and advantages of the present invention, and the manner of their attainment, will become apparent from the following description of a preferred embodiment of the invention taken in conjunction with the accompanying drawings wherein:

FIG. 1 is perspective view of a collapsible container in its erected condition on which the present invention may be incorporated and practiced,

FIG. 2 is a perspective view of the collapsible container in a partially erected condition and showing three of the cables of the hoist mechanism of the present invention;

FIG. 3 is a perspective view of the collapsible container in the fully collapsed condition;

FIG. 4 is a perspective view of the collapsible container in a partially erected condition with the end panels and portions of the roof and sidewall panels removed;

FIG. 5 is a partially schematic view of the winches and drive shaft of the hoist mechanism of the present invention mounted in the floor of the collapsible container;

FIG. 6 is an enlarged sectional view taken along lines 6--6 of FIG. 5 and showing the spring biased sheave assembly associated with one of the cables of the hoist mechanism shown in FIG. 5;

FIG. 7 is a fragmentary schematic view of one cable of the hoist mechanism of the present invention trained over pulleys on a pivotally mounted corner post in a vertical position; and,

FIG. 8 is a schematic view similar to FIG. 7 and showing the corner post rotated to a position between the vertical position and a horizontal position of the corner post.

Referring now to the drawings in greater detail, the hoist mechanism 8 (FIG. 5) of the present invention finds particular advantageous use in a collapsible container of the type indicated at 10 in FIGS. 1 to 4. This container 10 includes end walls 11 and 12 (FIG. 3) pivotally mounted on a base or floor 14 and inwardly folding sidewalls 15 and 16 (FIG. 4). The sidewalls 15 and 16 are hingedly connected at the upper edge thereof to a roof panel 18 (FIG. 4). To collapse the container 10, the roof panel 18 is lowered with the sidewalls 15 and 16 folding inwardly as best shown in FIG. 4. After the sidewalls 15 and 16 of the container 10 have been folded inwardly with the roof panel 18 lowered on top of the folded sidewalls 15 and 16, the end walls 11 and 12 of the container are pivoted inwardly and downwardly over the roof pane 18 to a collapsed position shown in FIG. 3. One of the end walls 11 has door panel sections 20 and 22 which are hingedly connected to corner posts 26 and 28 of the end wall 11 and the other end wall 12 has a single end panel 31 secured between corner posts 32 and 34 of the end wall 12. Each of the corner posts 26, 28, 32 and 34 is pivotally connected at the lower end thereof to a corner of the base 14 such as the lower end 36 of the corner post 26 is pivotally connected to the corner 38 of the base 14. As best shown in FIG. 4, the corner posts 26, 28, 32 and 34 form upstanding supports for the roof 18 and the sidewalls 15 and 16. It will be understood, that although not shown, suitable latches and keepers are provided for releasably securing the roof panel 18 to the upper beams 39 and 40 of the end walls 11 and 12.

Referring now to FIG. 5, the hoist mechanism 8 includes four cables 41-44 of each of which is anchored at one end to one of four winches 45-48 mounted in the base 14. A portion of each cable 41-44 is coiled on one of the winches 46-48 and the remaining portion of each cable is directed over one of four cable tensioning devices 49 and one of four guide pulleys 50, to one of the corner posts 26, 28, 32 or 34 where it is trained over lower and upper guide rollers or pulleys 51 and 52 (FIG. 2) to the upper end 53-56 of each corner post 26, 28, 32 and 34. The other end of each cable 41-44 extends from the upper end 53-56 of one of the corner posts 26, 28, 32 or 34 for connection to the roof panel 18 at spaced apart locations thereon. These locations are essentially at the four corners 57-60 (FIG. 4) of the roof panel 18.

The four winches 45-48 are driven by a common drive shaft 61 which is rotatably mounted on the base 14 and extends across the base 14 generally parallel to the pivot axis of the end walls 11 and 12. The drive shaft 61 has drive sockets 62 and 63 at either end thereof which are adapted to receive a mating projection of a suitable rotary power device (not shown) such as an electric motor. The drive connection from each of the winches 45-48 to the drive shaft 61 includes a gear box 66-69 connected to each winch 45-48, a first shaft portion 71-74 connecting each gear box to one side of a slip clutch 76-79, a second shaft portion 81-84 connecting the other side of each slip clutch 76-79 to a first sprocket 86-89, and a chain 91-94 connecting each sprocket 86-89 to a second sprocket 96-99 mounted on the drive shaft 61.

As best shown in FIG. 6, each of the cable tensioning devices 49 includes a spring 106 which is secured at one end 108 to a frame member 110 which forms part of the base 14 and which is positioned in the center thereof extending parallel to the sidewalls 15 and 16. The other end 112 of the spring 106 is connected to a sheave assembly 113 which includes a pulley block 114 connected at one end 115 to the spring 106 and at the other end 117 to a pulley 118. One of the cables, in this instance cable 44, is trained over the pulley 118. A U-shaped bracket 120 forming a guideway for the spring 106 and the end 115 of the pulley block 116 has two leg portions 121 and 122 which are secured by suitable fasteners 123 to the frame member 110 and a bight portion 124 which forms a stop for the end 115 of the pulley block 116.

Although FIG. 4 shows the cables 41-44 connected to the roof panel 18 at the upper edge thereof, it is preferred that the cables 41-44 be connected to the roof panel 18 at a point below the plane of the roof panel 18. For this purpose, the cables 41-44 are each connected to a lug on a flange 124 which is secured to the roof panel 18 and which extends downwardly therefrom parallel to the sidewalls 15 and 16 as best shown in FIGS. 1-3. In this way, when the roof panel 18 is raised to its fully raised position, the portion of the cable 41 extending from the upper end 53 of the corner post 26 will be extending downwardly at a significant angle with respect to the horizontal. It will be appreciated that if the roof panel 18 was not secured to the cables in this manner and a small angle existed between the cables 41-44 and the horizontal when the roof panel 18 was in its fully raised position, a large tension force would be required on the cable to provide the vertical force needed for holding the roof panel in the raised position prior to the latching of the roof panel 18 to the end walls 11 and 12.

To ensure that the flanges 124 do not adversely affect the nesting position of the end walls 11 and 12 over the roof panel 18 and the base 14 when the container 10 is in the collapsed condition, the base 14 is provided with recessed portions 125 near each corner of the base 14 in the area below the ends of each of the sidewalls 15 and 16. These recessed portions 125 are of a similar configuration as the flanges 124 so that each flange 124 can be received in the space formed by each recessed portion 125.

Also, to prevent the cables 41-44 from extending along the sides of the base 14 and then upwardly over the side edges of the base 14 and under the corner posts such as the corner 26, a guide lug portion 126 is provided on the base 14 adjacent each of recessed portions 125 for guidingly receiving respective ones of the cables 41-44. In this way, the cables 41-44 are kept out of the "way" when the end walls 11 and 12 are folded over the base 14 as shown by the position of the cable 41 in FIG. 3.

In the operation of the hoist mechanism 8 for raising the roof panel 18, it will be appreciated that it is desirable to have each of the cables 41-44 shorten its length uniformly so that the roof panel 18 will remain horizontal as it is raised and also so that the corners 57-60 of the roof panel 18 will reach their upward limit of travel at approximately the same time. To raise the roof panel 18 and shorten the lengths of the cables 41-44 uniformly, the four winches 45-48 are driven in synchronized relationship by the drive shaft 61. However, even with the synchronous drive, the cables 41-44 may not be uniformly shortened since each of the cables is not necessarily wrapped uniformly on its associated winch 45-48 due to the tendency of the winches 45-48 to scramble wind the associated cable 41-44 instead of winding the cable 41-44 in a spiral wrap, layer by layer. Also, because of the tolerances in the various parts of the hoist mechanism 8 and the container 10 and because of the uneven stretching or shrinking of the cables 41-44 after the container 10 has stood in an erected or collapsed condition for a period of time, the respective lengths of each of the cables 41-44 extending from each of the winches 45-48 to a corner 57-60 of the roof panel 18 will vary.

To compensate for differences in the lengths of the portion of each cable 41-44 extending from each winch 45-48 to each corner 57-60, each winch for the slip clutch 76-79 associated therewith. Although the clutch 76-79 are shown in the drive connections between the drive shaft 61 and the winches 45-48, it is to be understood that they can be situated in the drums of the winches 45-48. These clutches 76-79 compensate for the differences in the cable lengths by slipping when the corner 57-60 of the roof panel 18 has reached its upward limit of travel before the other corners, the tension on the cable 41-44 connected to that corner 57-60 will be increased by the torque placed on the associated winch 45-48 until a predetermined torque (relative to the maximum tension allowable on the cables 41-44) is reached where the slip clutch 76-79 will slip. In this way, continued rotation of the power drive shaft 61 to complete the raising of the other corners 57-60 to their upward limit of travel will not cause damage to the cables 41-44 connected to the corners 57-60 which have already reached their upward limit of travel or to any other part of the hoist mechanism 8.

Accordingly, the slip clutches 76-79, prevent damage to the hoist mechanism 8, align the roof panel 18 when it is raised to its fully raised position, ensures that the corners 57-60 are raised to their upward limits of travel, maintains the corners 57-60 at these upper limits and ensures that the portion of each cable 41-44 extending from each winch 45-48 will be shortened to its minimum length regardless of the way in which it was wrapped on the winch 45-48 to which it is connected.

It will be understood that all the winches 45-48 are usually over wound to the point where the slip clutches 76-79 slip to ensure that each corner 57-60 is raised to its upward limit of travel. When this is done the spring 106 of each of the sheave assemblies 114 is fully extended to the stop 123, it being understood that the tension placed on the cables 41-44 by each of the cable tensioning devices 49 is less than the tension necessary to cause the slip clutches 76-79 slip. In this way, the cable tensioning devices 49 are in a position to take up slack such as when the upper and lower sections of the sidewalls 15 and 16 (FIGS. 1 and 2) are pulled outwardly to place these sections in a vertical upright position and when the corners 57-60 are locked in place. It will be understood that with each cable 41-44 having its own cable tensioning device 49 the corners 57-60 of the roof panel 118 may be locked one at a time or simultaneously without causing slack in any one of the cables 41-44. Also, it will be understood that when the sections of the sidewalls 15 and 16 are pulled outwardly to place them in a vertical upright position the middle portion of one or both of the sidewalls 15 and 16 may be pulled "overcenter" past the vertical position such that the upper and lower sections of the end walls 15 and 16 are inclined outwardly. If this should occur, the cable tensioning devices 49 will compensate for the slack by movement of the spring 106 in the guideway 120.

The cable tensioning devices are provided for preventing slack from developing in any of the cables at any position of the roof panel 118. In particular, the cable tensioning devices 49 "pickup" slack when the roof panel 118 is lowered to its lowermost position. Thus, if the cables 41-44 are unwound unevenly so that one of the corners 57-60 reaches its lowermost position before the other corners, the cable tensioning device 49 associated with the cable 41-44 connected to the corner 57-60 will "pickup" the slack. Of course it is to be understood that when the roof panel 18 is being lowered, the tension on the cables 41-48 is related to the weight of the roof panel 118 supported by the cables 41-44. Thus, on the unwinding of the cables 41-44 from the winches 45-48 to lower the roof panel 118 to its lowermost position, the spring tensioning devices 49 will pick up some of the slack when one or more of the winches unwinds more cable than the other winches. However, it will be understood that the cable tensioning devices 49 cannot compensate for all the slack developed on continued unwinding of cable from the winches after all of the corners 57-60 have reached their lower limit of travel.

Thus, the cable tensioning devices 49 serve to pick up slack when the roof panel 118 is lowered to its lowermost position so that loose cables in the base 14 will be prevented, and when the roof panel 118 is raised to its uppermost position and then locked in place, and, as will be more fully described in connection with the description of FIGS. 7 and 8, the cable tensioning devices 49 serve to pickup slack caused by the folding of the end walls 11 and 12 over the roof 18. Also, it is to be understood that the cable tensioning devices 49 can take other forms and can be located in other positions. For example, the cable tensioning devices can take the form of a spring and stop mechanism mounted in the drum of each winch for maintaining tension on the cables 41-48.

As indicated in FIG. 7, when the corner post 26 is in a vertical position, the length of the cable 41 extending from the guide roller 52 to the corner 57 of the roof panel 118 will be equal to L.sub.1. However, as the corner post 26 is lowered about its pivot axis as indicated in FIG. 8, the length L.sub.2 of the cable 41 from the pulley 52 to the corner 57 will not necessarily be equal to the length L.sub.1. In some cases it will be more and in other cases it will be less. However, neither excess tension or slack will be developed in the cable 41 since the spring 106 of the cable tensioning device 49 associated with the cable 41 will move outwardly or inwardly to compensate for the increase or decrease in tension on the cable 41. It will be understood that an increase or decrease in tension in the other cables 41-44 when the other posts 28, 32 and 34 are lowered will be "picked up" by the cable tensioning devices 49 in like manner.

Although the hoist mechanism 8 of the present invention has been described with particular reference to its use in a collapsible container it is to be understood that the hoist mechanism 8 may find advantageous use in other applications where it is necessary to periodically move a horizontal panel between a fully lowered position and a fully raised position and where it is desirable to have a hoist mechanism which will maintain the panel essentially horizontal during the raising and lowering thereof by reason of devices which will automatically compensate for stretching or shrinking of the cables and for unequal winding of the cables on the winches of the hoist mechanism. Moreover, although the hoist mechanism 8 has been described with reference to pivotable upstanding supports 26, 28, 32 and 34, it is to be understood that it can be used with a frame structure having rigid upstanding supports.

Claims

I claim:

1. A mechanism for raising and lowering a panel or like member on a frame structure which includes a base and upstanding support means, said mechanism comprising at least three winches which are mounted on said base and which are operatively connected to a common drive means, a pair of upper and lower guide means associated with each of said winches and mounted on said upstanding support means, a length of cable associated with each of said winches and having one portion thereof coiled on its associated winch and another portion which is trained over said guide means associated with said winch, each of said cables having a first end anchored to its associated winch and a second end which is connected to said panel, said second ends of said cables being connected to said panel at spaced apart locations thereon, torque responsive means associated with each of said winches for stopping rotation of the associated winch when a predetermined tension is placed on said cable anchored to said associated winch, and tensioning means for continuously applying tension to each of said cables to prevent slack from developing at any time in any one of said cables.

2. The mechanism as defined in claim 1 wherein said torque responsive means includes a slip clutch in the drive connection from said drive means to said winch.

3. The mechanism as defined in claim 1 wherein said upstanding support means includes four upstanding corner posts, four winches are mounted on said base, and said frame structure is part of a collapsible container, said panel forming the roof for said container and said container including first and second oppositely facing sidewalls hingedly connected to said base and said roof and first and second end walls pivotally connected to said base, each of said endwalls including two of said upright corner posts with panel means therebetween.

4. The mechanism as defined in claim 1 wherein said tensioning means includes a spring means having a fixed end and a free end, said fixed end being connected to said base, a sheave assembly including a pulley block connected to said free end of said spring means and a pulley mounted on said pulley block, said cable being trained over said pulley and said sheave assembly being adapted to move transversely of the axis of rotation of said pulley against the tension of said spring means when tension on said cable is increased and decreased.

5. The mechanism as defined in claim 4 wherein said tensioning means includes a guideway which guidingly receives a portion of said pulley block and said spring means, said guideway having stop means positioned to limit movement of said pulley block.

6. In a collapsible container of the type having a base, end walls pivotally connected to said base, sidewalls hingedly connected to said base and a roof panel hingedly connected at each side edge thereof to said sidewalls, the improvement comprising a hoist mechanism mounted in said base and including a plurality of winches, a cable secured at one end to each of said winches and having a portion extending to said end walls, upper and lower guide means on said end walls for guiding portions of each of said cables to the top of said end walls, said cables having end portions which extend from said top of said end walls to said roof and are secured to said roof at spaced apart locations thereon, and means for rotating said winches from outside of said container, said hoist mechanism providing a self-contained means within said container for raising and lowering said roof and said sidewalls connected to said roof between an erected condition and a collapsed condition of said container.

7. The hoist mechanism as defined in claim 6 including torque responsive means associated with each of said winches for stopping rotation of each of said winches when a predetermined tension is placed on one of said cables connected to one of said winches.

8. The hoist mechanism as defined in claim 6 including tensioning means for continuously applying tension to each of said cables to prevent slack from developing at any time at any one of said cables.